How Bobsledding Works

By: Tracy V. Wilson & Patrick J. Kiger  | 

bobsledding
The Latvian team competes in the 4-man bobsled during the during the IBSF Sanctioned Race, a 2022 Beijing Winter Olympic Games test event, at the Yanqing National Sliding Center in Beijing Oct. 26, 2021. WANG ZHAO/AFP/Getty Images

If you've ever hit a patch of ice while driving your car, you've experienced a very tiny piece of what driving a bobsled is like. On an icy road, there's almost no friction between your tires and the road surface, so you can't steer very well. And any sudden moves, like hitting the brake, can send you spinning out of control.

So imagine if your car was open at the top and back — like a bobsled — and that the patch of ice lasted for almost a mile. Not a mile of straight, level road, either — a mile that's downhill and full of dramatic curves. That's what being in a bobsled is like. Drivers and crew slide down a hill on a track, or run, that's full of twists and turns. A wrong move can cause a dramatic crash.

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Most of the world calls the sport bobsleigh, though Americans know it as bobsled. But no matter what you call it, bobsledding is a fast-paced sport that relies on a precise combination of skill and physics. Bobsleigh has been a part of every Winter Olympics since the first one in 1924, with the exception of the 1960 games in Squaw Valley in California. At the 2022 Winter Olympics in Beijing, it's one of three sliding sports on the program, along with the skeleton and luge (more on those later). Athletes at the games will compete for 12 medals in bobsled events, including two in a new event, the women's monobob [source: IOC].

In this article, you'll learn about the athletes that make up a bobsled team, their training and their equipment. You'll also learn about bobsled runs and the physics behind bobsledding.

The Team

bobsled
Bobsled teams include either two or four athletes who steer, brake and add to the overall weight of the bobsled. Jennifer Wenzel/Icon Sportswire/Corbis/Getty Images

Racing a bobsled requires three things — a team, a bobsled (or bob) and a track. The team includes one, two or four athletes who steer, brake and add to the overall weight of the bobsled. (Men race in teams of two and four, while women, who got their initial two-person team event in 2002, had a single-person "monobob" event added at the 2022 games in Beijing [source: Mather]. The bob has an aerodynamic design and smooth runners so it can go as fast as possible. The track, generally made of concrete, has a solid ice surface. On the way down, bobsleds reach speeds of 80 miles per hour (130 kilometers per hour), even around curves. Crashes are common.

It's easy to see that being a bobsledder requires bravery and a good sense of balance. But making it down the run requires more than just coordination and nerve. Bobsleds weigh hundreds of pounds. The driver and brakeman on a two-person team (and the crewmen or push athletes in four-person teams) have to get the bob moving from a complete stop. They have to run as fast as they can, then jump inside the bob before the first curve [source: Borden].

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For these reasons, most bobsledders have backgrounds in other strenuous sports, like American football or track and field. During tryouts, prospective members have to prove their abilities in sprinting, jumping, pulling and lifting. Training isn't limited to taking a bobsled down a frozen run — there's lots of running, jumping and lifting weights. Crewmen and brakemen in particular do a lot of weightlifting, since they shoulder most of the burden for getting the bob going [source: Barroso].

Without any traction on the ice, it would be impossible for the team to move the bob. So, everyone on the team wears spiked shoes for better traction. Bobsledders also wear skintight, aerodynamic suits to help reduce drag on the way down the run. Everyone on the team must wear a protective helmet, usually with a full-face visor or a pair of goggles [source: British Bobsleigh & Skeleton]. Most drivers wear gloves, but some go barehanded for better contact with the steering rings.

We'll look at these rings and the other components of the bobsled next.

The Bobsled

bobsledding
The components of a bobsled. The hull, also known as a cowling, is generally constructed of fiberglass and made of two separate sections. HowStuffWorks

Modern bobsled races are competitions between two-person or four-person teams. Bobsleds have the same basic components whether they are built to hold two or four athletes. Each bob has:

  • A steel frame
  • A fiberglass hull that's closed in the front and open in the back, also called a cowling
  • A movable set of front runners
  • A fixed set of rear runners
  • Collapsible push-bars for driver and crewmen
  • Fixed push-bars for brakemen
  • A jagged metal brake on a lever, used only after the bob crosses the finish line
  • A steering system

The International Bobsleigh & Skeleton Federation (IBSF) sets rules for the composition and dimensions of each of these components, as well as the total weight of bobsleds. Bobsled manufacturers work closely with bobsled teams and designers to make the best sled design.

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Each type of bob has a minimum weight when empty and a maximum weight with bobsledders and their equipment. Weight limits for bobsleds are:

  • Two-man: minimum 384 pounds (170 kilograms) when empty, maximum 860 pounds (390 kilograms) with crew and equipment.
  • Two-woman: minimum 284 pounds (129 kilograms) when empty, maximum 715 pounds (325 kilograms) with crew and equipment
  • Four-man: minimum 463 pounds (210 kilograms) when empty, maximum 1,390 pounds (630 kilograms) with crew and equipment [source: IBSF].

Heavier sleds go faster, so teams that do not reach the maximum occupied weight may add ballasts to make their bob heavier. Officials weigh the sleds at the end of the run to make sure they meet the weight requirement. The hull, which is also known as a cowling, is constructed of fiberglass. It is closed in the front and open in the back so bobsledders can hop in and out. The hull cannot be transparent or so flimsy that it breaks apart in crashes. Hulls are typically made in two pieces, but steering comes from the front runners, not from movement in the hull [source: IBSF].

The steel runners themselves are blunt. They're polished until very smooth, minimizing the friction between them and the ice. Since narrow runners further reduce friction and are faster, the IBSF has rules covering runner width. Applying plating, coating or lubricant to the runners is illegal, as is heating them. Race officials electronically measure the temperature of the runners before the race and compare it to a reference runner that has been exposed to air for at least an hour. A temperature difference of more than 4 degrees Celsius (7 degrees Fahrenheit) between the bob's runner and the reference runner results in disqualification [source: IBSF].

Until the 1960s, bobsledders used a steering wheel to steer the bob. Now, drivers use a steering mechanism that consists of two pieces of rope attached to a steering bolt that turns the front frame of the bobsled. The driver can pull on the rope with his or her right hand to steer the sled to the right, and with the left hand to steer to the left. The brake, located at the end of a lever between the brakeman's knees, stays in place until after the bob crosses the finish line [source: IBSF].

Next, we'll look at how the athletes use the steering rings, handles and other parts of the bobsled when racing.

The Race Track

bobsledding
The Yanqing National Sliding Center track was built for bobsled, skeleton and luge competitions for the 2022 Winter Olympic Games in Beijing, China. The track features 16 turns, and the world's first 360-degree turn. Feature China/Barcroft Media/Getty Images

A bobsled race takes place on a specially built track called a run. The IBSF has standards for all new bobsled runs, which must also be usable for luge and skeleton races. There are 18 bobsled runs in the world, and 16 have IBSF approval. IBSF standards regulate the length, curve construction, vertical drop and centrifugal force the bobsledders experience in curves. Whenever possible, new tracks follow the curves of the terrain to minimize environmental impact.[source: IBSF]

Of all of the bobsled runs in the world, only one, the St. Moritz-Celerina located in St. Mortiz, Switzerland, uses entirely natural snow and ice. The rest of the world's bobsled runs are made from metal and concrete. Before the race, people cover the concrete with snow, then soak the snow with water. The resulting ice forms the surface for the race.

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Bobsledders begin the race in a push-off stretch. This is a straight stretch that's wide enough to allow the bobsledders to push the bob. The athletes have to run as fast as they can — this push and gravity are the bob's only sources of speed for the entire race. During the push-off, any ballast that the team has added to bring the bobsled up to the maximum weight is a liability. Even though there is very little friction, a heavier bob is harder to push.[source: IBSF]

The push-off takes about six seconds. A good start is crucial — a lead of a 1/10 of a second at this point can result in a lead of 3/10 of a second by the end of the race. After pushing off, the bobsledders jump from the track into the bob and crouch in an aerodynamic position. Usually, the driver gets in first, and the brakeman gets in last. The driver and crewmen, if there are any, fold their handlebars down.

At this point, the race is mostly up to the driver and gravity. Using very precise movements, the driver steers the bob down the run. Crewmen shift their weight when necessary in turns. The driver's aim is to find the line — the ideal path down the track. We'll look more at the line and how physics affect the bobsled's course next.

The Physics of Bobsledding

bobsledding
The German team competes in 2-man bobsled during the IBSF Bobsleigh International Sanctioned Race, part of a 2022 Beijing Winter Olympic Games test event, at the Yanqing National Sliding Center in Beijing Oct. 25, 2021. WANG ZHAO/AFP/Getty Images

What determines who wins a bobsled race? Basically, it comes down to physics. Victorious competitors are the ones who are most successful at maximizing acceleration of their sleds at the start of the run, and then minimizing other forces that tend to slow down the sled. But accomplishing that takes a combination of good equipment and a skilled team [source: Osborn].

Winning a bobsled race starts long before the push-off stretch — it starts with the design of a fast, efficient bobsled with good aerodynamics, so that it minimizes the resistance of the air. A bobsled design is tested in wind tunnels, adjusted and then tested again, in order to minimize the air drag [source: Osborn].

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There's also the challenge of maximizing acceleration, which is dependent upon how weight is distributed on a sled by the design. Bobsled makers utilize lightweight carbon fiber in the shell, so that the weight is shifted to the lower part of the sled. That also enables the sled to handle turns better [source: Osborn].

Another crucial part of minimizing the forces that slow down a sled are the runners, the metal blades that ride on the ice surface. They're coated and polished to reduce the amount of friction [source: Osborn].

While a well-designed sled is essential, the biggest factor in the equation is the team itself. All of the competing teams have a standard amount of mass, so the amount of force is that a particular team generates makes the difference. Good runners are able to push the sled faster than slower ones, which is one reason why some teams recruit track sprinters to do the pushing. Because the team only gets a chance to push at the start of the race, a good team can build an advantage that will last to the finish [source: Osborn].

In the course of their race, thought, it's important for a team to conserve their acceleration. That's why the push athletes position themselves in a tight tuck behind the driver, in order to create as little drag as possible. They also shift their weight to help the driver steer [source: Osborn].

In the end, all of these physical forces and athletes' actions lead to a very tight race. Often, the winning team's time is only a few hundredths of a second faster than that of the second-place team.

Bobsledding History

bobsled
Two man bobsled champions Ivan Brown and Alan Washbond in action at the 1936 Winter Olympics, which was held at Garmisch-Partenkirchen, Germany. Hulton Archive/Getty Images

Bobsledding began in 1877 in Davos, Switzerland, when people added a steering wheel to a normal sled. The first bobsledding club formed in 1897 in St. Moritz, Switzerland. Most of the first bobsled runs were snow-covered roads, and for years it was a popular recreational sport, particularly for the wealthy. It had the sort of popularity that skiing has today. The sport's name comes from the way early teams bobbed their heads to try to gain more speed on straight portions of the run [source: IOC].

Bobsledding has been an Olympic event since the first Winter Olympic Games in 1924 in Chamonix, France. At that time, the only competition was a four-man race. Two-man events were added at the 1932 games in Lake Placid, N.Y. Only men competed at the Olympic level until the 2002 games in Salt Lake City, when two-woman teams began competing [source: IOC].

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The only Winter Olympic Games that have not included bobsledding were the 1960 games in Squaw Valley, California, when the organizers declined to build a bobsleigh run, because only nine nations had indicated that they would send competitors [source: IOC].

Until the 1950s, most bobsledders were big and brawny. But in 1952, new rules governing the maximum weight of a bobsled and its passengers went into effect. At that point, bobsledders became highly-trained athletes who were very strong but light enough to fit the rules' weight requirements. Teams from all over the world have competed in bobsledding. Though Germany, Canada, Austria, the USA and Switzerland are the traditional powerhouses, the competition including those from countries known for their warm climates. Jamaica's bobsleigh team not only qualified for the 2022 Winter Olympics for the first time in 24 years, but for the first time made the grade in three different events—the four-man sled, the two-man bob and the women's monobob [source: IOC].

Check out the links on the next page for lots more information on bobsledding and other Olympic sports.

Originally Published: Feb 13, 2006

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More Great Links

  • Barroso, Mark. "The Gold Medalist Workout." Men's Journal. (Jan. 17, 2022) https://www.mensjournal.com/health-fitness/gold-medalist-workout/
  • Bobskeleton.org.uk. "How Have Bobsled Designs Changed?" Bobskeleton.org.uk. (Jan. 17, 2022) https://bobskeleton.org.uk/?p=43
  • Borden, Sam. "In the Back of the Bobsled, the Not-So-Scenic Route." New York Times. Feb. 21, 2014. (Jan. 17, 2022) https://www.nytimes.com/2014/02/22/sports/olympics/nothing-to-see-here-the-life-of-a-bobsled-brakeman.html
  • Britannica. "Bobsledding." Britannica.com. (Jan. 17, 2022) https://www.britannica.com/sports/bobsledding
  • British Bobsleigh & Skeleton. "Bobsleigh Kit." British Bobsleigh & Skeleton. (Jan. 17, 2022) https://www.thebbsa.co.uk/the-sports/bobsleigh/kit/
  • British Bobsleigh & Skelton. "Technique." British Bobsleigh & Skeleton. (Jan. 17, 2022) https://www.thebbsa.co.uk/the-sports/bobsleigh/technique/
  • "Everything You Need to Know about Bobsled." Washington Post, 1998. (Jan. 17, 2022) http://www.washingtonpost.com/wp-srv/sports/longterm/olympics1998/sport/bobsled/articles/bobsled.htm
  • International Bobsleigh & Skeleton Federation. "International Bobsleigh Rules, 2019." (Jan. 17, 2022) https://www.ibsf.org/images/documents/downloads/Rules/2019_2020/2019_International_Rules_BOBSLEIGH_am_cl.pdf
  • CBC. "What are the differences between bobsled, luge and skeleton?" CBC. (Jan. 17, 2022) https://www.cbc.ca/cbckids/olympics/pyeongchang2018/blog/what-are-the-differences-between-bobsled-luge-and-skeleton
  • International Olympic Committee. "History makers: Jamaica qualifies three bobsleigh teams for Beijing 2022." (Jan. 17, 2022)
  • International Olympic Committee. "Olympic bobsleigh at Beijing 2022: Top five things to know." Olympics.com. (Jan. 17, 2022) https://olympics.com/en/news/olympic-bobsleigh-at-beijing-2022-top-five-things-to-know
  • International Olympic Committee. "Squaw Valley 1960." Olympics.com. (Jan. 17, 2022) https://olympics.com/en/olympic-games/squaw-valley-1960
  • Kuhn, Karl F. "Basic Physics: A Self-teaching Guide." John Wiley & Sons, Inc., 1979. ISBN 0471030112.
  • Mather, Victor. "All Women and All Alone: Monobob Leads New Events for 2022 Olympics." New York Times. Jan. 5, 2022. (Jan. 17, 2022) https://www.nytimes.com/article/monobob-winter-olympics.html
  • Osborn, Hannah. "The perfect slide: The science of bobsledding." Smithsonian Science Education Center. (Feb. 17, 2022) https://s.si.edu/3Gyss58

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